Added second test case to shoot(): Call on Coordinate without ship

src/main/java/de/tims/fleetstorm/matchfield/Coordinate.java

@@ -45,7 +45,12 @@ public class Coordinate {
 	}
 
 	public void shoot() {
-		this.setState(Coordinate.HIT);
+		if (this.state == Coordinate.SHIP) {
+			this.state = Coordinate.HIT;
+			return;
+		}
+
+		this.state = Coordinate.SHOT;
 	}
 
 }

src/test/java/de/tims/fleetstorm/matchfield/CoordinateTest.java

@@ -60,7 +60,8 @@ class CoordinateTest {
 	}
 
 	static Stream<Arguments> ShootFunctionFieldStates() {
-		return Stream.of(Arguments.of("Field State is HIT", new Coordinate(0, 0), Coordinate.HIT));
+		return Stream.of(Arguments.of("Field State is HIT", new Coordinate(0, 0), Coordinate.HIT),
+				Arguments.of("Field State is SHOT", new Coordinate(0, 1), Coordinate.SHOT));
 	}
 
 }